Revision History

New whole-genome sequencing and wastewater surveillance data reveal that measles has been spreading silently across the United States for months — possibly over a year — before clinical detection, raising serious questions about whether the country can retain its measles elimination status. With national kindergarten MMR vaccination rates falling below the 95% herd immunity threshold for five consecutive years and confirmed cases surging past 2,200 in 2025, the Pan American Health Organization is set to review the US elimination designation in November 2026.